A type of swelling in the scrotum that happens when fluid collects in the thin sac that surrounds a testicle.

Most hydroceles are present at birth. They're more likely to affect premature babies. Older children and adults also can get hydroceles. An injury to the scrotum or swelling called inflammation within the scrotum raises the risk of getting a hydrocele later in life. Infections, including those passed through sex, also raise the risk.

Often, the only symptom of a hydrocele is painless swelling of one or both testicles. The swelling might make an adult's scrotum feel heavy. In general, the pain gets worse as the swelling increases. Sometimes, the swollen area might look smaller in the morning and larger later in the day.

Hydrocele treatment sometimes isn't needed. In babies, the condition may go away on its own. If it doesn't, surgery may be needed. To remove the hydrocele, a surgeon makes a cut in the scrotum or lower stomach area. Afterward, a tube may be placed to drain fluid for a few days. A bulky bandage also may be needed.